Contour inspection device



Aug. 18, 1953 J. H. OSGOOD 2,643,912

CONTOUR INSPECTION DEVICE Filed Aug. 11, 1947 10 Sheets-Sheet 1 TRANfiRsE MOTION IN V EN TOR.

Aug. 18, 1953 J. H. OSGOOD CONTOUR INSPECTION DEVICE 10 Sheets-Sheet 2Filed Aug. 11, 1947 2 o 1 o 1 ..1 5 9 L 1 m 1 m INVENTOR.

Aug. 18, 1953 J. H. OSGOOD 2,648,912

CONTOUR INSPECTION DEVICE Filed Aug. 11, 1947 10 Sheets-Sheet 3 1 melfil 126 I A 1'25 E l 135 y/ INVENTOR.

1953 J. H. oseooo 2,648,912

CONTOUR INSPECTION DEVICE Filed Aug. ll, 1947 10 Sheets-Sheet 4INVENTOR.

10 Sheets-Sheet 5 SYNCHRONOUS MOTOR 509 IN UPPER STYLUS U N ITOFREPEATING DEVICE Aug. 18, 1953 J. H. ossobo CONTOUR INSPECTION DEVICEFiled Aug. 11, 1947 SYNCHRONOUS MOTOR 306 IN LOWER STYLUS UNIT OFREPEATING DEVICE SYNCHRONOUS MOTOR 306 GEARED TO STYLUS CARRIAGE OREPEATING DEVICE DIFFERENTIAL GENERATOR I09 IN TRACING DEVICEDIFFERENTIAL GENERATOR 110 IN TRACING DEVICE S NCHRONOUS GENERATOR 131 NUPPER STYLUS UNIT OF TRACING DEVICE SYNCHRONOUS GENERATORISO IN LOWERSTYLUS UNIT OF TRACING DEVICE SYNCH RONOUS GENERATOR 1'24 GEARED TOSTYLUS CARRIAGE OF TRACING DEVICE.

POWER SOURCE I'IO'VOLTS, 6O CYCLES, SINGLE. PHASE Aug. 18, 1953 J. H.OSGOOD 2,648,912

CONTOUR INSPECTION DEVICE Filed Aug. 11, 1947 10 Sheets-Sheet 6 IMAGE o3STYLUS 511 IMAGE 0F STYLUS 510 IN V EN TOR.

g- 9 J. H. oseoon 2,648,912

CONTOUR INSPECTION DEVICE Filed Aug. 11, 1947 10 SheetsSheet 7 HVVENTOR.

Aug. 18, 1953 J. H. ossooo CONTOUR INSPECTION DEVICE l0 Sheets-Sheet 8Filed Aug. 11, 1947 mmxw 7 INVENTOR.

. J DMT 1953 I J. H. bsGooD 2 ,648,912

' CONTOUR INSPECTION DEVICE Filed Aug. 11, 1947 10 Sheets-Sheet 9 APOWERSOURCE @110 vow-s, so CYCLES, SINGLE PHASE figgg 'fig k' g Jgfi:{gg

UPPER SYNCHRONOUS GENERATOR 131 INSTYLUS UNIT TRACING DEVICE.

LOWER SYNCHRONOUS GENERATOR 130 IN STYLUS UNIT TRACING DEVICESYNCHRONOUS MOTQR 4 22 IN REPEATING ARMS UNIT RECORD\NG DEVICESYNCHRONOUS GENERATOR 42o GEARED SYNCHRONQUS MOTOR 124 GEARED To TOPAPER DRIVING ROLHRECORDWG DEVICE STYLUS CARRIAGE,TRAC.ING DEVICE PUSHBUTTON CYCLE STARTING SWZIECZIH MlGROSWlTCH 139 MOUNTED AT LIMIT OFCARRIAGE TRAVEL TRACING DEWCE o STOP $222325? CYCLEN ROLL. RECORDING IIIDEVICE STARTING RELAY g INVENTOR.

Aug. 18, 1953 J. H. ossooo CONTOUR INSPECTION DEVICE l0 Sheets-Sheet 10Filed Aug. 11, 1947 Patented Aug. 1 8, 1953 UNITED STATES PATENT OFFICECONTOUR INSPECTION DEVICE John Hazen Osgood, Claremont, N. H.

Application August 11, 1947, Serial No. 768,039

13 Claims. 1

This invention relates to a contour inspection device which may be usedfor the inspection of objects as to form and dimension, and moreparticularly to a device which facilitates the inspection of objectsdefined by complex curved surfaces such as turbine blades, propellerblades, and the like.

The rapid advances made of recent years in the turbine field have beenaccompanied by an ever increasin need for accurate and more efiicientmeans and methods of inspection to meet the requirements for the massproduction of turbine blades and buckets. However, the inspection ofthese and similar objects presents many difficulties not encounteredwhen inspecting objects having flat and simple curved surfacescharacteristic of ordinary machine elements. This is especially true ofobjects assuming a complex form manifested by variations in both pitchand cross-sectional area, and further, by the presence of both concaveand convex surfaces. That common forms of inspection devices cannot beused for this type of inspection it is apparent, and in general thosewhich have been devised for the purpose, such as special types ofmanually operated gauges and indicators, are of such a complex nature asto require operation by an experienced and skilled person, even thenconsuming an excessive amount of time.

A device which has been used most effectively for the routine inspectionof simple objects is the well known optical comparator. Briefly, itcomprises a system of optical comparison, the image of the object to beinspected being compared against a standard drawing or outline of theobject on a translucent screen. A source of light behind the objectcasts a shadow or image of the object which is then subjected tosuitable magnification in an optical system and reflected upon thescreen to be compared against the standard. While the results obtainablewith optical comparators are commendable, it is difiicult to foreseehow, at the present state of the comparator art, such a device may beused without modification to inspect the complex objects as have beenreferred to hereinabove. Another limitation of the usual comparator, aswell as many other inspection devices, is that a permanent record of theinspection results is not made. Such a record is often desirable.

Accordingly, this invention has as a purpose the provision of a devicewhich may be used with an optical comparator to adapt it for the routineinspection as to form, dimensions, and angular relationships, of objectsdefined by complex curved surfaces. A further purpose is to provide adevice for the inspection of complex curved surfaces which willpermanently record the inspection results, and which will present arecord from which the form, dimensions, and angular relationships may bedetermined. A still further purpose is to provide an inspection deviceof the nature described which may be operated by an unskilled personwith a minimum of instruction.

These and other purposes appearing hereinafter are accomplished by thepresent invention, an understanding of which may be had by reference tothe accompanying drawings and the descriptive matter relating thereto.In the drawings,

Fig. 1 is a front view, partly in section, of a tracing unit embodyingthe principles of the present invention.

Fig. 2 is a side view, partly in section, of the tracing unit of Fig. 1.

Fig. 3 is a view, partly in section, illustrating a preferred method ofgearing synchronou generator 124.

Fig. 4 is a complete side view of synchronous generator 124.

Fig. 5 is a View, partly in section, showing a tracing stylus 104 andits manner of attachment to synchronous generator I3l.

Fig. 6 is a side view of a repeating unit used in one embodiment of thepresent invention.

Fig. 7 is a rear View of the repeating unit shown in Fig. 6.

Fig. 8 is a schematic diagram of an electrical system for connecting thetracing and repeating units of the precedin figures.

Fig. 9 is a representation of an optical comparator screen showing themanner of comparing the repeating styli images against standard sectionson the screen.

Fig. 10 is a side view of a recorder used in another embodiment of theinvention.

Fig. 11 is a plan view of the recorder shown in Fig. 10.

Fig. 12 is a plan view of the recorder repeating arm gear housing unit421, partly in section.

Fi 13 is an end view, partly in section, of the gearing arrangementshown in Fig. 12.

Fig. 14 is a schematic diagram of an electrical system for connectingthe tracing and recording units.

Fig. 15 is an alternate electrical system which may be used to obtainpower amplification toy drive the stylus carriage of the tracing unitinstead of the direct synchronous generator-motor connections of Fig.14.

Briefly stated, the inspection device contemplated by the presentinvention comprises a pair of styli mounted in a tracing unit andmovable in three rectangular coordinates, so that the styli may traverseany point of an object to be inpected, electrical means comprising asynchro or selsyn system to transmit intelligence resulting from thevarious motions of the styli, and a repeating or exhibiting unit wherethe motions are reproduced, permitting observation of the form,dimensions, and angular relationships of the object under inspection.

In one form of the invention the repeating unit is adapted to be used inconjunction with anoptical comparator so that an object may beinspected, the image of which ordinarily cannot be projected onto acomparator screen because of interference with the light path by thewarped and complex surfaces of the object. This particular embodimentwill be considered first; For convenience, the reference numerals to thetracingunit are in the 100 series, to any intermediate electricalsystem, the 200 series, and to the repeati ng-unit, the 300 series.

Referring to Figs. 1 and 2 which show two views of the tracing unit, theobject to be inspected, I! I,'is fixed in relation to the base I612 ofthe tracing unit by means of a suitable fixture not shown. The tracingof object I M is accomplished by'styli II3and IM which are designed tomove in the vertical plane as they traverse any point of the object.Motion of the styli in the longitudinal direction of object IUI, thatis, in the direction as indicated by Fig. 2, is accomplished throughframe I05fwhich'is'mounted on base I02 by suitable means such as ballsH35 and It? and gib plates I'IJB 'and 38a.

Frame N is shown as one casting extending from the base I92 to the topof the tracing unit. This motion is transmitted to the repeating unit ofFigs. '6'and7, in part by means of difierential synchronous electricgenerators I09 and iii mounted in the base I02 and geared to a rack atIII-"mounted in frame I65. A'stop mechanism H2 attached to frame I05,and stop bar IIS are provided to limit the motion of frame W5, andthus-facilitate the inspection of the object It: in severalpredetermined parallel planes, depending upon the number and spacing ofthe notches I I inbar I'I3.

Motion of the styli in the transverse direction of object IGI, that is,in the direction as indicated byFi'g: Land in a direction 90 degreesfrom the motion-of the frame I95, is accomplished by carriage I I5 whichis mounted in frame I65 by means of balls I IEand II'I, ways IIS andlit, and plate I26. Way H8 is provided with stops I2I and I22 to limitthe motion of the carriage at the extremities of its travel. The motionof carriage H5 in turn isaccomplished by the'rotation of crank I 23which is geared through the armature shaft of synchronous electricgenerator I2 by means of gear train I25 and pinion I26 (shown in Figs. 3and 4) to rack I21 mounted on the carriage I I5. Generator I24 transmitsthe motion of the carriage'to the repeating unit shown in Figs. 6 and'7. The two styli I03 and IM are provided with replaceabletips I 28 andI29 of suitable shape and sizesuch as spherical with a radius of sayabout & inch, and are geared to two synchronous electrio-generators I30and I3I which are mounted in fiiied'positions on carriage I I5. Thesegenerators transmit the motions of the styli in the vertical plane tothe repeating unit. A convenient manner'of gearing the styli is shown inFig. 5. For example, stylus I04 is racked with teeth I32 to permitengagement with pinion I33, which by means of gear I34 and pinion I35causes rotation of generator shaft I38 when the stylus is moved in thevertical plane. A spring I31, of a type similar to a watch main spring,is mounted on shaft I38 to maintain a positive pressure on the stylus atall times. This keeps the stylus in constant contact with the objectunder inspection, and eliminates the worst condition, of. backlash whichwould tend to effect the system, since the pressure of the pinion teethon the rack teeth of the stylus is always in the same direction. Bychoosing a suitable gear ratio, say 8 to 1, between the gear I t'andgenerator pinion I35, any backlash at this point may be reduced so thatit is no longer serious;

The repeating unit shown in Figs. 6 and '7 is similar in many respectsto the tracing unit. However,"it is designed to be positioned such thatthe repeating styli 3 I I3 and 3! I arewithin the effective lensaperture till of an optical-comparator, and

the frame 302 is thereforeprovided with clamps 363' and 3134 so that theentire unit may be so p0; sitioned. Carriage 305 may be mounted in frame332 in the same manner as the tracing carriage was shown to be mountedin its unit, and its mo tion is accomplished by synchronous electricmotor 353% which is geared to rack 30'! on the-carriage.

rotation of the armature in generator IZt. On the carriage 365 two moresynchronous electric motors 3&8 and 399 are mounted. To these are gearedthe two repeater styli, tltand '3II respectively. The same type ofmechanism as was used for gearing the tracing styli H13 and HM tosynchronous generators I39 andIBI of the tracing unit may be used togear the repeater stylifilfi and 3H to the synchronous electric motors338 r.

and 3th The motors 388 and 399 are connected electrically to generatorsI36 and I3I. respectively, T

so that the. motions of the tracing styli are repeated in space by therepeating. styliB I I3 and 3 II An electrical system for the connectionof the.

tracing and repeating units heretofore described i shownin Fig. 8.Referring to this, the preced-.

ing figures, and Fig. 9,. the mode of operation is as follows.

The objectv It! to be inspectedis properly it. The carriag H5 is thenmoved intrans:

verse relationto object IQI. bymeans of crank.

I23, causing the styli to engage theobject and move in accordance withits contours. causes the rotors of stylus synchronous generators iBfiand53I. to revolve, creating electricalimpulses therein. These impulses aretransmitted by transformer action, through ;the sta:

tors and rotors of differentialgenerators Ide and H0 to the rotors ofsynchronous motors 308 and 399 in the repeating unit. The result is arotation of the motorrotorsin .the repeating unit in accordance with.the rotation, of the. respective generator rotors in thetracing unit.

Since the rotors of the differential generators do notmove at any timeduring this or any other..- tracing operation, the effect is the same asif 7. the synchronous generator rotors in ,thetracing nit had, b en cnnected. d rectly to .thesyris.

The motor 3D6is electrically connected to synchronous generator I2 l-ofthe tracing unit and is energized by impulses received as a result ofthe This.

5 chronous motor rotors in the repeating unit. Such a connection isactually used to effect movement of the repeating unit carriage 305; ascrank I23 is operated to move carriage II5, it also rotates the rotor ofsynchronous generator I24, and consequently, the rotor of synchronousmotor 306, geared to the repeating unit stylus carriage, moves in step.Thus, the motions undergone by the tracing styli are duplicated in spaceby the repeating styli of the repeating unit. The latter, being withinthe effective lens aperture of an optical comparator, permits of theformation of their respective images by a light source on one side andthe magnification and projection onto a comparator screen of theseimages by the comparator optical system on the other side of the styli.The screen, having been provided with one or more large crosssectionaloutlines of object IOI corresponding 'to the plane or planes inspected,facilitates a comparison of the paths travelled by the repeating styliimages against a standard. A comparator screen with several sectionsdrawn thereon is illustrated by Fig. 9, showing the manner in which thestyli images may appear on the screen. The first plane of inspection,such as the one near the hub of object IOI described above, maycorrespond to section A on the screen. Since the images will move inaccordance with the actual contours of the object under inspection, anydeviations from the standard sections may be noted.

Upon completion of the inspection in one plane, such as that onereferred to above, a second plane of inspection may be selected at anypredetermined point of the object. The frame :05 of the tracing unit isthen moved by lifting stop mechanism H2 and manually sliding the unit onits base to the point where the styli reside in the desired plane. Thestop mechanism is then released to engage the notch in stop bar II 3corresponding to the plane to be inspected, and fixing the frame I05 inthat plane. This movement will effect the rotation of rotors R and Rwith respect to the stators S and s (shown in Fig. 8) of thedifferential generators I09 and H located in the base I02 of the tracingunit. Such motion will cause the rotors of synchronous motors 308 and309 of the repeating unit to experience the same degree of rotation,this rotation being in the same direction, since the differentialgenerator rotors move in the same direction. The net result is aunidirectional vertical movement of the repeating styli, say upwards.Because the motion is fixed and controllable, the standard of comparisonmay be positioned on the comparator screen above and at the properdistance from the cross-sectional outline required for the first planeof inspection. Movement of frame I of the tracing unit to apredetermined section of the object will then automatically position theimages of the styli to the corresponding standard section on thecomparator screen, such as from the first plane of inspection, A, shownin Fig. 9 to that plane corresponding to section B shown immediatelyabove A. The operator may then place the tracing styli in position onthe object, and by manipulating crank I23, inspect this next section inthe same manner as has been described for the first, following whichsections C and D may similarly be inspected.

It is recalled that the difierential generator rotors remain in a fixedposition during each tracing operation so that the repeating styli willmove in step with the tracing styli. Con versely, when the rotors of thedifferential generators are moved, the tracing styli synchronousgenerator rotors remain substantially fixed, so that the repeating styliwill move in step with the rotors of the differential generators. Theeffect of any movement of the tracing styli while the rotors of thedifferential generators are moved will be automatically corrected whenthe operator sets the tracing styli in place for a trace. However, meansmay be provided for locking the tracing styli during this operation ifdesired.

The reason for incorporating the differential generators in the tracingunit is to speed the operation of the entire inspection device bypermitting the inspection of a number of sections of an object withoutchanging the comparator screen.- Where this convenience is notimperative, the differential generators may be eliminated, and directconnections made between the tracing styli generators andthe repeatingstyli motors, although this would necessitate a comparator screen changefor each section inspected.

Another form of the invention embodies'the use of a recording unitinstead of the optical comparator repeating unit, so that a continuousrecord of the inspection results maybe obtained. For this purpose thesame tracing unit of Figs. 1 and 2 may be'used, although with somemodification. The differential generators I09 and H0 are no longernecessary and need not be used, but the frame I05 is movable as beforeand may be locked in place by the stop and bar mechanism at any desiredplane of inspection. Synchronous generator I24, instead of being usedas. a synchronous generator, is a synchronous motor and is operated fromthe recorder,'although the mechanical means for moving carriage II5,namely crank I23 and its associated mechanism, remains unchanged. Theframe I05 is provided with a microswitch I39 which is operated byadjustable stop I40 on the carriage 'I I5 to automatically limit theoperation and motion of carriage II5 after a trace. Stylus synchronousgenerators I30 and I3I function asdescribed hereinabove.

The recording unit is shown in Figs. 10 and 11. A roll of paper 40I ismounted in holders 402 and 403 by means of clamps 404 and 405 held inplace by spring actuated members 406 and 401. The paper is fed over aplate 408 and then over a driving roll 409 which is provided with teethor sprockets at the ends thereof to engage with perforations on thesides of the paper, thus achieving a positive drive of the paper.Another roll, 4I0, presses against the driving roll, being under springpressure, and maintains close contact between the aper and the drivingroll. From the driving roll the paper passes over a curved plate M I,which guides it out to the end of the recording unit where a blade M2 isprovided to facilitate tearing off the record after it has been made.The driving roll 409 is actuated by a constant speed electric motor 4I3driving through a coupling and worm gear 4I4 to gear M5 on the drivingroll shaft 4IB.' The other side of the driving roll shaft is gearedthrough gears 4| 1 and M0 to pinion 4III of a synchronous electricgenerator 420. This generator is electrically connected to synchronousmotor I24 of the tracing unit to-effect motion of the tracing carriageII5 when the recorder is operated. The housing 42I, shown in detail "inFi '12 "ans 13 enta ns two synchronous electric motors 422 'and' 423; 1care operated by impulses received frcm" 'ynchrono'us' generators I30 and-I3I of thetraeihg unit; Eacli" s'$ chifonous motor is geared; threatena suitable gear train, such as pinion 424, gear 425, pinion 426 and gear421 for one, '-az"1"cl'piiiioh42'8, gear 429, p'i'nion 430, and'fg'ear"431 "for the other',"to repeating arms'asz 'and lflrespectively. Thesearms swing in an'ai'c, arid'are lightly ieaaea'by means of springs 433"and 435 to maintain 'u'i'i direetional'pres'sure of the gear teeth'a'tall times, and further to provide a return for-the arms. The actualfecordiiigon'thepaper is accomplished by pointsass' and 431 whichcontain a Writing compound, oi' an eleetric petential may be'u'tili'z'edbetween-the points jafid iateaoste'register impressions on aneIectro-sensitive' paper. The latter procedure presents littlediiiiculty' since housing 421 is eleetr'ic'ally 'msiuatee from the mainrecorder frame'438by insmatingbushi'ngs such assume andahinsulating-plated; The circuit may be from a source'ofelectrical'potential through the housine'42L arms 432 andfl33, pointsl36 and 431, plate 408, main frame438, 'ar'id'back't'o' thesdurce;

Fig; "14"shovi'stheeleetrical connections between the tracing .and'recording" units. Referring tothi's a'n'dto Figs; 1; 2, 10 ahd11,the'mode of operation isa's'followsr The object I 01 to'be ms'pectedisplaced in a fixed'positio'n with respect to the base I 9201? thetracing unit. Using the" stop mechanism I'I2 andst pbarl l3; theframe'isfixed in any desiredplanebf'inspstirni. Thestylus' carriagelfiis tnemmafiuany moved by crank I23" to a po- "sition vi hei'etliestylfare adjacent to the object "IOT, infie'ald lfl'ssftb start 'th'etlade. The pushbutton cy'clesta'rting' switch '20I i's pu'shed,thereby'caufs g' starting rela 202 to close, and 'a hold- --ing con act26'3 oiithe 'relaykeeps therelay fenergizedfahdc sea, oncethecycle'hasbeen started. At the ametinie, anotnemontacr 12M or "the may;co plte's' the circuit of "recorder morornlsyput n'g th'erecorder pap'r'inumotion. This nergize ynchroneus generator" 420 geared 'to'the aperdriving r011; and'the mpuisesrrem this generator are "traitisriritte'd'-to synchronous motor I2 I' of"the"traemg unit causing the-tram i ig eariagerifi to traverse the object I9 I. {As -soon a' s th'e'carriage'mov'es 'over'the objects; styn 103 and I6 eiieif'gizesynchronous;generators I30 "and I3I of'the*tra'cing unit.Ilies'imp'1ilses' 'in turn are trahs'initted'to 'synchronous"motors422'and"423 of the"reco'rder,' 'causingrecorder farm's 432 and33to'desc'ribe thecontoursoftheobjeet undeninsp'ec'tion upon the'recorderpaper. The motions of the arms will be in proportionto the motions"ofth'e styli I03 and.Iilll'multiplied bya 'factor of amplification,this factor being afunction of thejphysical proportions of the'arr'nsand their geartrains. For optimum results,;the distance the recorderpaper. travels: should be in proportion to'th'e distance thefcarriage II;of the'traiifgunit; travels, multiplied by thesame 'faetorofamplifi'cati'on as that of. thearmsl This "factor; however, arisesfromthe physical pro- 1 pdrtiohs fftne earing "between the drivingroll sraps thefsynjchro nous" generator "up; The

sham

8 I30 on "the 'tr'acingcarriage' contacts -themicro switch 139 whichopens the holding circuit of relay 202. This de eriergizes thedrivingimotor H3, stopping the recorder paper. and the tracing carriage,and, since the synchronous motor "system is de-energized, carriage "I15may be re.-

set to its starting position byimeans of crank 123. 'Any other sectionmay then betraced using the above procedure. :If electrical means'isusedto register the contours on the recording, paper, relay 202 may beprovided with an additional con'tact'to permit the application of'wanelectrical potential between the recorder points and plate 408.

Whereas the recorder and tracing unit may :be of light weightconstructionfor a great many applications of the invention, :it. isconceiv ble that for. some purposes, namelywhere relatively largeobjects are to be inspected, a much heavier "tracingunit would benecessary. The-question then arises whether or not the. stylus carriagesynchronous motor I24 woulddeliver suifieient torque to overcome theinertial and frictional resistance of such a'system. Large synchronousmotors and generators are available, or a means for providing poweramplification, asis-showndn Fig. 15 may be used. Here, the impulses fromsynchronous generator 420 oftherecordingjunit are fed tothe'stator S of,a synchronous control transformer IdI. The carriagel'liofthe tracingunit is in this case operated by a .D. G. motor 142 instead of asynchronous motor I24 which is replaced by the D. 0. motor., Rotor R-ofthe synchronous control transformer is geared to-the D. C. motor so thatthe position of theD.- C. motor armature may begcompared, an electricalsense, to the, position of the armature of synchronous generator 420,Avoltage isproduced in rotor R of synchronous control transformer I4Iwhich is proportional to the difierence in-the-angular positions of thetwo farmatures, that is, the 'voltageis proportional to the error in theposition of the armature of the D. ;C. motor. This error voltage is .theoutput off-the synchronous control transformer, I4! and is fed into aconventional vacuum tubecontrol amplifier 205 which delivers impulses to.the v field coils-of a ,D. C. generator 208,, operated by C. motor 201.The A. C. motor is driven from'the-same power source as that which isfed to synchronous generator 420. Output from the D. C. generator 206drives D. 0. motor I42, the field off which is supplied with a D. C.source-of power by field supply rectifier 208. Switch 209 may correspond .t o contacts -263 and 204 of'the starting relay shown in Fig. 14 topermit resetting of the-carriage after each trace.

When the rotor of: synchronous generator 420 is moved from a state .ofrest-through some small angle, .a new direction ofifield is induced inthe stator of synchronous 'controltransformer MI V The rotor winding ofthe control transformer, which has ben'ir'l "a state of zero inducedvoltage. will. now develop" a" voltage due'to the new directionofffield' of the stator. This'volt'a'ge,

increased by theamplifierv 205Ian'd'fe'd"to the field' coils 10f D. Qgenerator wfi," will cause the D. Cjmotor to rotate, Because the rotorof the control transformer is geared to the D." C.'m'otor,

angle; equal to thgt thrbugh which the SyllchronouS "generator 420 hasmoved;

Power amplification of the impulses resultin from any other motions ofthe contour inspection device may be achieved in a similar manner, usinga separate control transformer, amplifier, D. C. motor andmotor-generator set for each motion.

The synchronous electric generators and motors of the present inventionas referred to throughout the specification and in the appended claimsare of the self-synchronous type commonly called selsyns. I

It is perhaps apparent, but nevertheless significant, that the practiceof the present invention, using either the optical comparator or therecorder embodiments, will permit the inspection and measurement of thepitch or angular relationships of an object in addition to itscrosssectional contours. By observing the degree of slant from a normfor any particular crosssection, its pitch and the pitch of the objectat that plane of inspection may readily be determined.

Although the embodiments of the invention specifically illustratedherein relate to a device using two styli, for some purposes whereinformation regarding but one surface is desired, only one tracingstylus and one repeating stylus or recording arm would be necessary. Onthe other hand, more than two styli may be advantageously used to obtainsimultaneous inspection at any desired number of planes within practicallimits by modifications which become apparent to those skilled in theart, they being familiar with the present invention.

It is also to be noted that the invention may be practiced by using oneor more styli which are fixed in two coordinates, but movable inaccordance with the contours of the object under inspection, and movingthe object in relation to the styli by means similar to that employedfor moving the styli as set forth above. Then, the relative motionbetween the styli and the moving object may be resolved along twocoordinates, and by synchronous electric means stransmitted toexhibiting means to be observedas previously disclosed.

The invention is particularly advantageous where the large scale routineinspection of coma plex curved objects is desired. It provides a fast,efficient, and accurate inspection device which may be operated by anunskilled person, in contrast to common devices of the same characterwhich are slow and require the extensive training of skilled personnelbefore such persons are qualified to operate them. However, once aperson familiar with the present invention has set up the inspectiondevice and outlined a simple test procedure, any intelligent unskilledperson can inspect even the most complex objects. Furthermore, by simplychanging the electrical connections between the tracing and exhibitingmeans from one exhibiting means to another, which may be accomplished byan elementary switching mechanism, the device becomes adapted to producea permanent record of the inspection results. Such a record is oftendesirable for research work on objects of the character j described tocompare their contours before and after operational tests are performedthereon.

Many changes and modifications may be made in the physical constructionand in the electrical systems of the invention without departing fromits spirit, and it is understood that the invention is not to be limitedin its broadest aspect to such details or exemplifications as have been10 used to describe and illustrate it. The invention may be variouslypracticed and embodied within the scope of the claims hereinafter made.

What I claim is:

1. A device for inspecting the contours of an object comprising a base,a surface engaging member thereon movably mounted to respond to contourvariations of an inspection object, means for effecting engagement andrelative movement between said surface engaging member and the object ina series of predetermined parallel planes of inspection, a carriageelectrically synchronized with said means in response to said relativemovement in each plane of inspection through a two member selsyn systemelectrically connected therebetween, said means being connected to onemember and said carriage to the other, presetting means to fix therelative positions of said surface engaging member and said objectprogressively in each of said planes of inspection, a contour followeron said carriage movably mounted in synchronization with said surfaceengaging member in accordance with contour variations through a twomember Selsyn system electrically connected therebetween, said surfaceengaging member beingconnected to one member and said follower to theother, a diiferential generator operatively controlled by saidpresetting means and electrically connected to said Selsyn systemsynchronizing said surface engaging member and said follower to movesaid follower a predetermined distance when the relative positions ofsaid surface engaging member and said object are changed from one planeof inspection to another.

2. A device for inspecting the contours of an object comprising a base,a frame movably mounted thereon in a defined path and means to fix saidframe in any predetermined position with respect thereto, a carriagemovably mounted on said frame for motion in a path angularly displacedfrom the path of said frame, a surface engaging member on said carriagemovably mounted to respond to contour variations of an inspectionobject, a second movable carriage electrically synchronized with saidfirst movable carriage through a two member Selsyn system electricallyconnected therebetween, said first carriage being connected to onemember and said second carriage to the other, a follower on said secondcarriage movably mounted in synchronization with said surface engagingmember in accordance with contour variations through a two member selsynsystem electrically connect ed therebetween, said surface engagingmember being connected to one member and said follower to the other, anda differential generator operatively controlled by the movement of saidframe and electrically connected to said selsyn system synchronizingsaid surface engaging member and said follower to move said follower apredetermined distance when said frame and surface engaging member aremoved from one plane of inspection to another. a

A device for inspecting the contours of an ob ect comprising a base, aframe movably mounted thereon in a defined path and means to fir: saidframe in any predetermined position with respect thereto, a carriagemovably mounted on said frame for motion in a path angularly displacedfrom the path of said frame, a surface engaging member on said carriagemovably mounted to respond to contour variations ofan inspection object,a second movable carriage electrically synchronized with said firstmovable carriage through a two member Selsyn system electricallyconnected therebetween, said first carriage being connected toone memberand sa d second carriage to the other, a follower on said secondcarriage movably mounted in synchronization with said surface engagingmember In accordance with contour variations through a two'member selsynsystem electrically connected therebetween, said surface engaging memberbeing' connected to one member and said follower to the other, a sourceof light to provide a light beam impinging on said follower and anoptical system for projecting the image of said follower onto acomparator screen, said second movable carriage coacting with saidfollower means to exhibit the contour path of said follower on saidcomparator screen when a section of said object undergoes inspection,and a differential generator operatively controlled by the movement ofsaid "frame and electrically connected to said selsyn systemsynchronizing said surface engagin member and said follower to movesaidfollower a predetermined distance when said frame and surfaceengaging member are movedfrom one plane of inspection to another.

4. A device for inspecting the contours of an object comprising a, base,a frame movably mounted thereon in a defined path and means to fix saidframe in any predetermined position with respect thereto, a carriagemovably mounted on said frame for motion in a path angularly displacedfrom the path of said frame, a surface engaging 'member on said carriagemovably mounted to respond to contour variations of an inspectionobject, a second base and a second movable carriage thereon electricallysynchronized with said first movable carriage through a two memberselsyn system electrically connected' therebetween, said first carriagebeing connected to one member and said second carriage to the other, afollower on said second carriage movably mounted in synchronizationwithsaid surface engaging member in accordance with contour variationsthrough a synchronous generator-motor selsyn system electrically connectedtherebetween, said surface engaging member'being connected to saidgenerator and said follower to said motor, and a differential gen eratoroperatively controlled by the movement of said frame and electricallyconnected to said selsyn system synchronizing said surface engagingmember and said follower to move said follower a predetermined distancewhen said frame and surface engaging member are moved from one plane ofinspection to another.

5.--A device for inspecting the contours of an object comprising a base,a frame movably mounted thereon in a defined path and means to fix saidframe in any predetermined position with respect thereto, a carriagemovably mounted on said frame for motion in a path angularly displacedfrom the path of said frame, a surface engaging member on said carriage'movably mounted to respond to contour variations'of an inspectionobject,'a second base and a second movable carriage thereon electricallysnchronized with said first movable carriage through a synchronousgenerator-motor selsyn system electrically connected therebetweensaid'first carriage having a driving connection with said generator andsaid second carriage having a driven connec tion with said motor, afollower on said's'econd carriage movably mounted in synchronizationwith said surface engaging member in accordance with contour variationsthrough a second synchronous generator-motor selsyn system electricallyconnected therebetween, said surface engaging member ha'vinga drivingconnection with saidgene'rator and said follower having a drivenconnection with saidmotor, and a differential generator operativelycontrolled by the movement cream frame and electrically connected to"said second selsyn system to move said follower a determined distancewhen said" frame and surface engaging member are moved from one'plane ofinspection to another.

61 A device for inspecting the contours of an object comprising a base,a frame movably mounted thereon in a defined path and means to fix saidframe in any predetermined position with respect thereto, a carriagemovably mountdd on said frame for motion in a path angularly displaceddegrees from the path of'said frame, a first synchronous generatorhaving a driven con nection with said carriage, a second synchronousgenerator on said carriage, a surface'enga fig member having a drivingconnection withfsaid second synchronous generator and movably mounted torespond to contour variations'ofan inspection object, a second base anda second movable carriage thereon electrically synchroni'zed with saidfirst movable carriage through a synchronous motor having a drivingconnection therewith and an electrical connectionwith" said firstsynchronous generator, a second synchronous motor on said carriage, afollower having a driven connection with said second synchronous motorand movably mounted in synchronization with said surface engaging memberin accord" ance with contour variations through an electrical connectionbetween said second synchronous generator and said second synchronousmotor, and a differential generator within said first base and frame,said differential generator having a driven connection with said frameand an electrical connection with said second synchronous generator andsaid second synchronous motorto move said follower a predetermineddistance when saidframe and surface engaging member are moved from oneplane of inspection to an- Qih 7. A device for inspectin the contours ofan object comprising a 'base'; a frame movably mounted thereon in adefined path and charac-' terized by lower and upperguides spaced apartby an upstanding member; means to fix said frame in any predeterminedposition with res'pect to said base; a carriage movably mounted on saidframe for motion in a path angularly displacedQO degrees from thepath'of said 'f'rarne, said carriage being characterized by lower andupper guided members spaced apart by an up standing member; a firstsynchronous generator having a driven connection with said carriage; asecond and a third synchronous enerator on said lower and upperguided'members respectively; a pair of opposed surface engaging members,each'having a driving connection with one of said second and thirdsynchronous generators and each being movably mounted to respond tocontour variations of a side of an inspection object; a second base alsocharacterized by lower and upper guides spaced apart by an upstandingmember; a second movable carriage thereon electrically synchronized withsaid first movable carriage through a synchronous motor having a drivingconnection therewith and an electrical connection with said firstsynchronous generator, said second carriage also being characterized bylower and upper guided members spaced apart by an upstanding member; asecond and a third synchronous motor respectively on said lower andupper guided members of said second carriage; a pair of opposedfollowers, each having a driven connection with one of said second andthird synchronous motors, and each being movably mounted insynchronization with said surface engaging member in accordance withcontour variations through an electrical connection between said secondsynchronous generator and said second synchronous motor and between saidthird synchronous generator and said third synchronous motor; and a pairof differential generators within said first base and frame and having adriven connection with said frame, each differential generator furtherhaving an electrical connection with one of said second and thirdsynchronous generators and motors to move said followers a predeterminedunidirectional distance when said frame and surface engaging members aremoved from one plane of inspection to another.

8. A device for inspecting the contours of an object comprising a base,a frame movably mounted thereon in a defined path and means to fix saidframe in any predetermined position with respect thereto, a carriagemovably mounted on said frame for motion in a path angularly displacedfrom the path of said frame, a pair of opposed surface engaging memberson said carriage, each being movably mounted to respond to contourvariations of a side of an inspection object, a second base and a secondmovable carriage thereon electrically synchronized with said firstmovable carriage through a two member selsyn system electricallyconnected therebetween, said first carriage being connected to onemember and said second carriage to the other, a pair of opposedfollowers on said second carriage, each being movably mounted insynchronization with a corresponding surface engaging member inaccordance with contour variations through separate synchronousgenerator-motor selsyn systems electrically connected therebetween, eachsurface engaging member being connected to a generator and each followerto a motor, and a pair of differential generators operatively controlledby the movement of said frame, each electrically connected to a selsynsystem synchronizing a surface engaging member and a follower to moveboth of said followers a predetermined unidirectional distance when saidframe and surface engaging members are moved from one plane ofinspection to another.

9. A device for inspecting the contours of an object comprising a base,a frame movably mounted thereon in a defined path and means to fix saidframe in any predetermined position with respect thereto, a carriagemovably mounted on said frame for motion in a path angularly displacedfrom the path of said frame, a surface engaging member on said carriagemovably mounted to respond to contour variations of an inspectionobject, a second base and a second movable carriage thereon electricallysynchronized with said first movable carriage through a two memberselsyn system electrically connected therebetween, said first carriagebeing connected to one member and said second carriage to the other, afollower on said second carriage movably mounted in synchronization withsaid surface engaging member in accordance with contour variationsthrough a synchronous generator-motor selsyn system electricallyconnected therebetween, said surface engaging member being connected tosaid generator and said follower to said motor, a source of light toprovide a light beam impinging on said follower and an optical systemfor projecting the image of said follower onto a comparator screen, anda differential generator operatively controlled by the movement of saidframe and electrically connected to said selsyn system synchronizingsaid surface engaging member and said follower to move said follower apredetermined distance when said frame and surface engaging member aremoved from one plane of inspection to another.

10. A device for inspecting the contours of an object comprising a base,a frame movably mounted thereon in a defined path and means to fix saidframe in any predetermined position with respect thereto, a carriagemovably mounted on said frame for motion in a path angularly displacedfrom the path of said frame, a surface engaging member on said carriagemovably mounted to respond to contour variations of an inspectionobject, a second base and a second movable carriage thereon electricallysynchronized with said first movable carriage through a synchronousgenerator-motor selsyn system electrically connected therebetween, saidfirst carriage having a driving connection with said generator and saidsecond carriage having a driven connection with said motor, a followeron said second carriage movably mounted in synchronization with saidsurface engaging member in accordance with contour variations through asecond synchronous generator-motor selsyn system electrically connectedtherebetween, said surface engaging member having a driving connectionwith said generator and said follower having a driven connection withsaid motor, a source of light to provide a light beam impinging on saidfollower and an optical system to project the image of said followeronto a comparator screen, and a differential generator operativelycontrolled by the movement of said frame and electrically connected tosaid second selsyn system to move said follower a predetermined distancewhen said frame and surface engaging member are moved from one plane ofinspection to another.

11. A device for inspecting the contours of an object comprising a base,a frame movably mounted thereon in a, defined path and means to fix saidframe in any predetermined position with respect thereto, a carriagemovably mounted on said frame for motion in a path angularly displaceddegrees from the path of said frame, a first synchronous generatorhaving a driven connection with said carriage, a second synchronousgenerator on said carriage, a surface engaging member having a drivingconnection with said second synchronous generator and movably mounted torespond to contour variations of an inspection object, a second base anda second movable carriage thereon electrically synchronized with saidfirst movable carriage through a synchronous motor having a drivingconnection therewith and an electrical connection with said firstsynchronous generator, a second synchronous motor on said carriage, afollower having a driven connection with said second synchronous motorand movably mounted in synchronization with said surface engaging memberin accordance with contour variations through an electrical connectionbetween said second synchronous generator and said second synchronousmotor, a source of light to provide a light beam impinging on saidfollower and an optical system for projecting the image of said 11-5gfollower onto a comparator screen, and a, differ- .ential generatorwithin said first base and frame, ,saidydiiferential generator having adriven connection With said frame and an electrical connection with saidsecond synchronous generator and said second synchronous motor to movesaid follower a predetermined distance when said .frame and surfaceengaging member are moved from one plane of inspectionto another.

12. A gauging mechanism for use in an electrically synchronized contourinspection device comprising a base, a frame movably mounted thereon ina defined path and means to fix said frame in any predetermined positionwith respect thereto, ,;a carriage movably mounted on said frame formotion in a path angularly displaced 90 degrees from the path of saidframe, a first synchronous generator having a driven connection withsaid carriage, a second synchronous generator on said carriage, asurface engaging member having a driving connection with said secondsynchronous generator and movably mounted to respond to contourvariations of an inspection object, .and a differential generator withinsaid base and frame, said differential generator having a. drivenconnection with said frame and being adapted for an electricalconnection with said second synchronous generator to impart to theimpulses from said second synchronous generator a further impulseWhenever said frame and surface engaging member are moved from one planeof inspection to another.

13. A gauging mechanism for use in an electrically synchronized contourinspection device comprising a base; a frame movably mounted thereon ina defined path and characterized by lower and upper guides spaced apartby an upstanding member; ineans to fix said frame in any predeterminedposition with respect to said base; a carriage movably mounted on saidframe for motion in a path angularly displaced 90 degrees from the pathof said frame, said carriage being characterized by lower and upperguided members spaced apart by an upstanding member; a first synchronousgenerator having a driven connection with said carriage; a second and athird synchronous generator on said lower and upper guided membersrespectively; a pair of opposed surface engaging members, each having adriving connection with .one of said second and third synchronousgenerators and each being movably .mounted to respond to contourvariations of an References Cited in the file of this patent UNITEDSTATES PATENTS Number Name Date 1,424,556 Cooke Aug. 1, 1922 1,612,120Hildebrand Dec. 28, 1926 1,967,080 .Dietze July 17, 1934 2,091,534Templin Aug. 31, 1937 2,136,134 Holley Nov. 8, 1938 2,143,233 WallaceJan. 19,1939 2,239,811 'Cuppers Apr. 29, 1941 2,302,572 Reason Nov. 17,1942 2,305,167 Kasper Dec. 15, 1942 2,357,790 Turchan Sept. 5, 19442,398,562 Russell Apr. 16, 1946 2,417,962 Cooke Mar. 11, 1947 2,424,031Heer July 15, 1947 2,433,585 Warner Dec. 30, 1947 2,437,639 Floyd Mar.9, 1948 2,451,155 DeBoer Oct. 12, 1948 2,476,312 Luety July 19, 19492,494,663 Lobosco Jan. 17, 1950 FOREIGN PATENTS Number Country Date586,071 England Mar. 6, 1947-

